Plenum and runners in one piece on a WBX

fastback · Post by **fastback** » Sat Mar 14, 2009 2:31 pm

mostly concerned about the engine and plenum/runners not expandig in the same rate... but hey it's both parts (almost all) is aluminum anyway..?right?
plan is to use shortend carb runners and weld it to a cusotom plenum.

Unkl Ian · Post by **Unkl Ian** » Sat Mar 14, 2009 7:57 pm

I think the manifold would be cooler than the rest of the motor.

If the manifold was heated with water, the expansion would be closer..

fastback · Post by **fastback** » Sun Mar 15, 2009 3:29 am

yes that'st true.
but the question is then will it be "to much" tension ..
if u compare with other engines like inline 4 ,5 and 6 sylinders they have sometimes manifold's in one piece.
but of course diffferent designs and some are cast iron heads that do not expand so much

tencentlife · Post by **tencentlife** » Sun Mar 15, 2009 2:16 pm

Which type of wbx intake system are you wondering about?

fastback · Post by **fastback** » Sun Mar 15, 2009 2:28 pm

planning to weld a plenum between these runners , making it one piece:

regis101 · Post by **regis101** » Sun Mar 15, 2009 2:57 pm

The angle of the dangle may not allow a one piece manifold to fit onto the head.

Unkl Ian · Post by **Unkl Ian** » Sun Mar 15, 2009 6:05 pm

With studs, that would be a problem.

tencentlife · Post by **tencentlife** » Tue Mar 17, 2009 7:02 am

I think you'd end up with overstress and perhaps cracking somewhere. If you water heat the manifold it would lessen, but not eliminate, differential expansion stress, but then you have a hot manifold making the intake air hotter, and a more complex thing to build vs. putting some tubing couplers in there which is simple and eliminates all those problems.

fastback · Post by **fastback** » Tue Mar 17, 2009 8:13 am

yes thats what i have come up with to.
and if i'm swapping head's or putting the plenum on another engine , tolerances will probably not make it fit right either.